title: Room-temperature study of iron gall ink impregnated paper degradation under various oxygen and humidity conditions: time-dependent monitoring by viscosity and X-ray absorption near-edge spectrometry measurements.
abstract: Many western manuscripts were written using iron gall inks. These inks can damage the paper via two major mechanisms: (a) acid hydrolysis, enhanced by humidity, and (b) oxidative depolymerization provoked by the presence of oxygen and free iron(II) ions. The degradation of unsized Whatman paper impregnated with different combinations of iron sulfate, gallic acid, and gum arabic was studied at room temperature in order to assess the relative importance of each mechanism. The samples were stored in various environments including a dry and/or an oxygen-free atmosphere. The cellulose depolymerization was monitored by viscometry and related to changes in the oxidation state of iron, determined by X-ray absorption near-edge spectrometry. The results indicate that residual amounts of oxygen (less than 0.1%) promote cellulose depolymerization, whereas the level of relative humidity has no impact. The cellulose depolymerization also appears closely correlated to oxidative mechanisms. Regarding the oxidation of iron, it only occurs in the simultaneous presence of oxygen and moisture, suggesting the occurrence of rustlike oxidative mechanisms. Finally, the presence of gallic acid has a strong influence, which is only partially explained by its capacity to reduce iron(III) to iron(II).
authors.affiliation: Centre de Recherche sur la Conservation des Collections, MNHN-MCC-CNRS, USR 3224, 36 rue Saint Hilaire, 36 rue Saint Hilaire, 75 005 Paris, France. rouchon@mnhn.fr
authors.forename: Véronique
authors.initials: V
authors.lastname: Rouchon
authors.forename: Maroussia
authors.initials: M
authors.lastname: Duranton
authors.forename: Cédric
authors.initials: C
authors.lastname: Burgaud
authors.forename: Eleonora
authors.initials: E
authors.lastname: Pellizzi
authors.forename: Bertrand
authors.initials: B
authors.lastname: Lavédrine
authors.forename: Koen
authors.initials: K
authors.lastname: Janssens
authors.forename: Wout
authors.initials: W
authors.lastname: de Nolf
authors.forename: Gert
authors.initials: G
authors.lastname: Nuyts
authors.forename: Frederik
authors.initials: F
authors.lastname: Vanmeert
authors.forename: Kevin
authors.initials: K
authors.lastname: Hellemans